EP2325070A1 - Front unit of an automobile comprising a front bumper shield provided with a beam enabling the attachment of at least one auxiliary device of the automobile - Google Patents

Abstract

The front assembly has fixation and support plates (20) equipped at front ends of upper girders (12) and lower girders (16) and connected together by a metal cross-piece (21) that extends opposite to the upper girders. A front bumper shield (8) comprises a monoblock frame (22) that is made of plastic material. Two posts (28) connect an upper bumper beam (24) with a lower bumper beam (26), and are formed to act as shock absorbers. The two posts are directly supported against the plates. The upper bumper beam extends above the metal cross-piece and the plates.

Description

The present invention relates to a front assembly of a motor vehicle, of the type comprising at least two pairs of front longitudinal members of a chassis of a motor vehicle and support and fixing plates arranged at the front ends of the longitudinal members, the plates being connected between them by a metal crosspiece extending opposite the upper longitudinal members.

Modern motor vehicles are designed to respond appropriately to different types of possible frontal shocks, such as low-speed shocks or "parking shocks", for speeds of 2.5 to 4 km / h (ECE42), medium-speed shocks or "reparability shocks", for a speed of about 16 km / h (Danner) and shocks at high speeds, for a speed of between 56 and 65 km / h.

Modern motor vehicles are also designed to protect pedestrians in the event of pedestrian impact, and in particular to protect the pedestrian's legs and hip.

It is possible to provide a front assembly comprising a metal upper bumper beam fixed to the ends of upper longitudinal members of a high track (main stretchers) via first metal shock absorbers reported on the upper bumper beam , and a lower bumper beam attached to the ends of lower longitudinal members of a lower track (cradle extensions) via second metal or plastic shock absorbers, attached to the lower bumper beam.

Nevertheless, such a front assembly is complicated and expensive to manufacture and install.

In addition, such a set does not integrate optimally with the rest of the equipment of the front part of the motor vehicle, that is to say that such equipment, such as cooling system, optics or other are arranged around the front assembly without particular connection between this assembly and these equipment. Complex attachment means must then be added to bind these different elements together.

An object of the invention is to provide a front assembly to suitably respond to pedestrian shocks and shocks at low and medium speed and allowing easy integration of other equipment from the front of the vehicle, while being simple and easy. having a low manufacturing cost.

To this end, the invention relates to a front assembly of the aforementioned type comprising a front bumper shield comprising a one-piece plastic frame formed of an upper beam and a lower bumper beam and two amounts connecting the beams. upper and lower bumpers, the frame uprights being configured to act as shock absorbers and fixed in abutment directly against the plates, the upper beam extending above the metal crossbar and plates.

• la poutre supérieure comprend des moyens de fixation d'au moins un équipement auxiliaire du véhicule automobile ;
• la poutre supérieure comprend au moins deux branches s'étendant sensiblement perpendiculairement au cadre vers l'arrière de celui-ci, lesdites branches comprenant des moyens de fixation d'un équipement auxiliaire du véhicule automobile ;
• la poutre supérieure présente des nervures s'étendant au moins sur la face avant de ladite poutre ;
• la poutre supérieure présente en outre des nervures sur sa face supérieure, lesdites nervures s'étendant en outre sur les branches ;
• la poutre inférieure comprend des moyens de fixation d'au moins un équipement auxiliaire du véhicule automobile ;
• l'ensemble avant comprend un élément d'absorption d'énergie, ledit élément étant disposé contre la traverse métallique et s'étendant sensiblement en travers du cadre ;
• les montants présentent une structure alvéolaire formée d'alvéoles s'étendant longitudinalement au travers des montants et débouchant sur la face arrière et/ou avant du bouclier;
• chaque montant comprend des premières alvéoles borgnes, fermées du côté de la face arrière et ouvertes du côté de la face avant, et des deuxième alvéoles borgnes ouvertes du côté de la face arrière et fermée du côté de la face avant ;
• l'ensemble avant comprend en outre un équipement auxiliaire s'étendant en regard de la face arrière du bouclier, ledit équipement étant fixé au moins à la poutre supérieure dudit bouclier par les moyens de fixation de ladite poutre additionnelle ; et
• l'équipement auxiliaire est fixé à la poutre supérieure par au moins un élément de liaison fixé aux moyens de fixation de la poutre supérieure, ledit élément de liaison étant agencé pour absorber les vibrations entre l'équipement auxiliaire et le bouclier.

According to other embodiments, the front assembly comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:

• the upper beam comprises means for fixing at least one auxiliary equipment of the motor vehicle;
• the upper beam comprises at least two branches extending substantially perpendicularly to the frame towards the rear thereof, said branches comprising means for fixing an auxiliary equipment of the motor vehicle;
• the upper beam has ribs extending at least on the front face of said beam;
• the upper beam further has ribs on its upper face, said ribs further extending on the branches;
• the lower beam comprises means for fixing at least one auxiliary equipment of the motor vehicle;
• the front assembly comprises an energy absorbing element, said element being disposed against the metal cross member and extending substantially across the frame;
• the uprights have a cellular structure formed of cells extending longitudinally through the uprights and opening on the rear face and / or front of the shield;
• each upright comprises first blind cells, closed on the side of the rear face and open on the side of the front face, and second blind cells open on the side of the rear face and closed on the side of the front face;
• the front assembly further comprises an auxiliary equipment extending facing the rear face of the shield, said equipment being fixed at least to the upper beam of said shield by the attachment means of said additional beam; and
• the auxiliary equipment is fixed to the upper beam by at least one connecting element fixed to the attachment means of the upper beam, said connecting element being arranged to absorb the vibrations between the auxiliary equipment and the shield.

The invention also relates to a front bumper shield for a motor vehicle of the type comprising a one-piece frame formed of an upper bumper beam and a lower bumper beam and two uprights connecting the upper and lower bumper beams. lower, said upper beam comprising means for attaching at least one auxiliary equipment of the motor vehicle, characterized in that it is intended to be integrated in a front assembly of a motor vehicle, the shield being intended to be integrated in an assembly before motor vehicle as described above, the amounts of shield being configured to act as shock absorbers and adapted to be fixed in abutment directly against the plates.

• la figure 1 est une vue schématique en perspective éclatée d'un ensemble avant selon l'invention ;
• la figure 2 est une vue schématique en perspective de l'ensemble avant de la figure 1 partiellement assemblé,
• la figure 3 est une vue schématique en perspective de l'ensemble avant de la figure 2 assemblé, et
• la figure 4 est une vue en perspective de trois-quarts arrière d'un ensemble avant des figures 1 et 2, un équipement auxiliaire étant fixé au bouclier dudit ensemble.

The invention and its advantages will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which:

• the figure 1 is a diagrammatic perspective exploded view of a front assembly according to the invention;
• the figure 2 is a schematic perspective view of the whole before the figure 1 partially assembled,
• the figure 3 is a schematic perspective view of the whole before the figure 2 assembled, and
• the figure 4 is a rear three-quarter perspective view of a front set of figures 1 and 2 , auxiliary equipment being attached to the shield of said assembly.

Subsequently, the terms of orientation, such as "longitudinal", "transversal", "forward", "backward", "above", "below", etc. by reference to the usual orientation of motor vehicles, illustrated on the figure 1 by the arrows S directed horizontally forwards in a longitudinal direction of the motor vehicle.

As shown on the figure 1 , a motor vehicle 2 comprises a frame 4 comprising a front portion 6, a front bumper shield 8 disposed at the front end of the front portion 6 to protect the front portion 6 in case of impact, and a skin 9 of pare shocks to cover the shield 8.

The front portion 6 includes a top track 10 comprising a pair of upper side members 12, or stretchers, and a lower track 14 comprising a pair of lower side members 16, which may be cradle extensions.

The upper longitudinal members 12 extend longitudinally and are spaced transversely from one another.

The lower longitudinal members 16 extend longitudinally and are spaced transversely from one another. The transverse spacing between the lower longitudinal members 16 is substantially equal to that between the upper longitudinal members 12.

The upper longitudinal members 12 are tared to collect a maximum axial force without buckling between 80kN and 100kN. The lower longitudinal members 16 are tared to collect a maximum axial force without buckling between 25kN and 45kN. On certain vehicles with gauge far from the average, the proposed rating ranges may differ slightly, without departing from the scope of the invention.

The upper longitudinal members 12 are provided to receive between them and to support at least partly a front face 18. The front face 18 is shown on the figure 1 schematically by a rectangle in mixed lines. In known manner, the front face 18 comprises a support frame carrying functional members of a cooling system of the powertrain of the vehicle and / or an air conditioning system, such as one or more radiator or a fan assembly. As shown on the figure 4 and as will be described later, the cooling system comprises a radiator 19 attached to the shield 8.

The front face 18 is partially set back towards the rear of the front ends of the upper and lower spars 12 and 16.

The front portion 6 includes a pair of mounting plates 20 disposed at the front ends of the upper and lower spars 12. Each platen 20 connects the forward end of an upper spar 12 to that of the adjacent lower spar 16 on the same side. Each plate 20 has the shape of a metal plate extending in a substantially vertical transverse plane. The plates 20 may be made of pressed steel, rolled, folded or light alloy.

The plates 20 are interconnected by a metal crosspiece 21 whose ends are fixed substantially opposite the upper longitudinal members 12, as shown in FIG. figure 1 . Thus, the metal cross member 21 is located at the height of the upper track 10 and more particularly binds the upper longitudinal members 12. The metal cross member 21 has for example a height preferably between 70 mm and 120 mm and has the function of opposing at the intrusion of a pole, a vehicle or any external rigid structure to the front face 18 in the event of impact against the motor vehicle. Between the longitudinal members 12 and therefore between the ends of the cross member, the metal crosspiece 21 has a curved shape forward so as to extend across the shield 8, as will be described later. This shape makes it possible to improve the aeraulic while preserving the cooling at the level of the radiator, by moving the metal beam away from the cooling unit. This geometry also allows the beam to benefit a better flexural strength during an axial impact of the vehicle, and thus effectively oppose the intrusion of a rigid obstacle inside the vehicle. The section of the beam may consist of an open profile (for example U-shaped or H) or closed, possibly partitioned, to improve its stiffness characteristics. The metal cross member 21 is fixed to the plates 20 by screwing or welding, for example.

The skin 9 is a front bodywork element of the vehicle and defining the outer curve of the vehicle.

The shield 8 is disposed between the skin 9, by which it is covered, and the front portion 6. It has the function, with the metal cross member 21, to absorb the impact energy at a low speed (ECE42 parking shock) and medium-speed shocks (RCAR compatibility, Danner repairability) in order to preserve the chassis 4, as well as to protect a pedestrian in the event of a pedestrian impact.

The shield 8 is fixed in longitudinal support against the plates 20. The shield 8 is disposed in front of the front face 18 so as to protect it, as well as the functional organs that it carries.

The shield 8 comprises a one-piece frame 22 formed of an upper bumper beam 24 extending above the high track 10, a lower bumper beam 26 located at the height of the lower track 16 and two amounts 28 connecting the bumper beams 24, 26 between them.

The bumper beams 24, 26 extend substantially transversely and horizontally. They are spaced vertically from each other. The uprights 28 extend substantially vertically between the bumper beams 24, 26.

The lower beam 26 serves to channel the energy of a shock to the uprights 28 in the event of a collision. In the same way, the metal crosspiece 21 aims to channel the energy of a shock to the plates 20 and the upper stretchers 12 in the event of a collision. The lower bumper beam 26, or "pedestrian bumper beam", also serves to protect the leg by stopping the shin in the event of a pedestrian impact.

The lower bumper beam 26 is arranged to impact the leg of a pedestrian below the knee, while the metal cross member 21 is provided to impact the leg of a pedestrian substantially to the right of the knee. For this purpose, the curved portion of the metal beam 21 is covered by an energy absorbing element 27, as shown in FIGS. figures 2 and 3 . This absorption element 27 is flexible and is for example made of expanded foam, as shown in the figures 2 and 3 .

Alternatively, the absorption element 27 is made of injected plastic material and has for example ribs promoting energy absorption. The element absorption 27 extends across the frame 22 of a post 28 to the other. It is fixed to the metal cross member 21 and / or to the uprights 28 by fastening means, such as latching means on the uprights 28 and / or gluing on the crossmember 21.

Advantageously, the lower bumper beam 26 is advanced relative to the rest of the frame 22 to provide adequate protection to the pedestrian. The lower bumper beam 26 has a U-section open horizontally rearwardly. Optionally, the lower bumper beam 26 comprises internal stiffening ribs (not shown).

The uprights 28 of the shield 8 are intended to serve as an energy absorber between the skin 9 and the plates 20, and to absorb the energy of a shock on the shield 8 at low speed or medium speed (Danner) .

Thus, the uprights 28 are able to be fixed directly in rigid support against the plates 20, without interposing additional shock absorbers reported between the uprights 28 and the plates 20, or between the plates 20 and the upper longitudinal members 12 and lower 16. This configuration differs significantly from the current state of the art.

For a motor vehicle whose mass is between 900 Kg and 1400 Kg, the energy to be dissipated in the event of a medium-speed shock (Danner) is traditionally between 8 KJ and 14 KJ, and more generally between 8 KJ and 12 KJ. Preferably, each upright 28 is provided to absorb an energy greater than 5 KJ in the case of a medium-speed shock (Danner), preferably between 8 KJ and 12 KJ.

Each upright 28 has a honeycomb structure comprising cavities 32, 34 extending longitudinally between a rear face 36 and a front face 38 of the uprights 28.

Each upright 28 comprises inverted blind cells comprising first blind cells 32, closed on the side of the rear face 36 and open on the side of the front face 38 (FIG. Figures 1 to 3 ), and second blind cells 34 open on the side of the rear face 36 and closed on the side of the front face 28 ( figure 4 ). The first cells 32 and the second cells 34 are arranged in staggered (or checkered).

The upper cross member 24 extends above the metal cross member 21. The upper cross member 24 comprises means for fixing at least one auxiliary equipment of the motor vehicle. According to the embodiment shown in the figures, these fixing means are provided on a branch 40 extending at each end of the upper beam 24. The branches 40, integral with the upper beam, extend substantially perpendicularly. to the upper beam 24 towards the rear of the frame 22. The branches 40 therefore extend in a substantially longitudinal direction toward the rear of the shield 8.

The branches 40 comprise fixing means 42, represented on the figure 4 , an auxiliary equipment of the motor vehicle, such as a radiator 19. The fixing means are for example formed by a notch for receiving complementary fastening means 44 provided on the radiator 19. The complementary fastening means 44 are for example formed by pins provided on the radiator and fitting into a respective notch of the branches 40. According to another embodiment, the fixing means 42 are formed by at least one orifice (not shown), on each branch 40 , receiving a complementary pin provided on the radiator 19 or a pin provided for engaging in a complementary orifice of the radiator 19. On Figures 1 to 3 no means of fixing the radiator 19 have been shown and they may be of any type suitable for receiving the auxiliary equipment of the motor vehicle.

According to an alternative embodiment, the radiator 19 is fixed to the branches 40 by means of at least one connecting element (not shown) arranged to absorb the vibrations that can propagate between the shield 8 and the radiator 19. connecting element is for example made of an elastomeric material having a certain flexibility while having sufficient rigidity to maintain the radiator 19 in position relative to the shield 8. Such a connecting element is more particularly known as the "silent box" ". Such an element has for example an orifice for receiving a radiator pin 19 and a pin receiving orifice provided on a branch 40 of the upper beam 24 forming a fastening means 42. According to one embodiment, two elements each of which attaches the radiator 19 to one of the branches 40 of the upper beam 24. According to yet another embodiment, the upper beam 24 does not comprise a branch 40 and the connecting elements are fixed to the end portions. of the upper beam 24.

According to alternative embodiments, the upper beam 24 further comprises means for attaching other auxiliary equipment of the motor vehicle, such as means for attaching optical supports or fastening means to wing spars provided on the body of the motor vehicle. The upper beam 24 may also comprise means for receiving the lock of the hood of the motor vehicle.

The upper beam 24 is arranged to have high rigidity and good bending strength in the vertical direction to resist snapping or tearing of the hood of the motor vehicle. In addition, it also has energy absorption characteristics in the event of impact against the motor vehicle. For this purpose, the upper beam 24 comprises ribs 46 extending at least over the front face of said beam 24, as shown in Figures 1 to 3 . According to an embodiment not shown, the ribs 46 further extend on the upper face of the beam 24 up to the branches 40. As shown in FIGS. Figures 1 to 3 , the ribs 46 are for example distributed between vertical ribs 48 spaced from each other longitudinally and ribs 50 in "X" extending diagonally between the vertical ribs 50. The ribs provided on the upper face of the upper beam 24 extend for example in "sawtooth". Alternative geometries can be used to impart the desired characteristics to the part.

According to the embodiment shown on the Figures 1 to 3 , the upper beam 24 further comprises cells 52 extending the uprights 28 on the sides of the front face of the upper beam 24.

The radiator 19 shown on the figure 4 is also attached to the lower beam 26, by fastening means such as the connecting elements 54, or "silentbloc", described above. According to an alternative embodiment not shown, the lower beam 26 comprises uprights carrying fastening means adapted to receive complementary fastening means provided on the radiator 19.

Each upright 28 is fixed directly to the corresponding plate 20, in contact and rigid longitudinal support against the plate 20. Each upright 28 covers most of the support surface offered by the plate 20 corresponding.

Each upright 28 is fixed on the corresponding plate 20 by screwing or gluing. This second solution is advantageous, insofar as it allows a good distribution of efforts. Indeed, the design constraints related to the assembly by screwing (metal inserts, holes, stiffening soles, spaces for the screwdrivers) are lifted, while the localized stresses and the risks of tearing caused by the screwing are very strongly mitigated. In addition, the chosen geometry formed of inverted blind cells disposed in staggered rows considerably increases the sizing surface at the rear of the uprights 28 and contributes to the favorable distribution of the forces.

The plates 20 high, or giant platinum, connecting each upper spar 12 to a lower spar 16, distributes the distribution of the efforts collected by the shield 8 to a high height in the vehicle, with the amounts 28 extending between the high and low channels.

The giant plates 20 provide a rigid bearing surface extended to the uprights 28, which allows the uprights 28 to work uniformly in compression in the event of impact, without bending in their median portion located vertically between the top 10 and the lower channel 14 This advantage allows a uniform design of the uprights 28, having similar cells uniformly distributed, demoldable longitudinally and intended to work mainly in compression. The architecture therefore differs radically from the structures without giant plates, the amounts of which must present a design intended for work in bending.

As a result, the vehicle equipped with a front assembly according to the invention is less intrusive when it comes into contact with another vehicle, which benefits inter-vehicle compatibility at low and medium speeds.

The size of the support provided by the plates 20 is advantageously between 100 and 180 mm in width, and between 350 and 450 mm in height, which corresponds to areas generally between 3.5 and 8 dm ² .

The honeycomb structure of the uprights 28 facilitates manufacture and gives the uprights a sufficient energy absorption capacity over a small depth (dimension along the longitudinal direction).

The frame 22 is obtained in one piece, for example by plastic injection molding. It can be demolded in a single direction corresponding to the longitudinal direction of the motor vehicle when the shield 8 is fixed on the frame 4. Thus, the frame 22 can be obtained in a simple manner, with a low manufacturing cost. The honeycomb structure of the uprights 28 makes it possible to reconcile large clearance angles (between 1 ° and 3 ° for example) and constant thicknesses, which is impossible with a traditional "waffle" type geometry. This trick increases the effectiveness of the absorption (reduced stroke, constant calibration with effort bearing), saves the longitudinal members and limits the weight and cost of manufacturing the shield 8. The parts obtained are therefore light and have material economy.

The cellular structure of the uprights also makes it possible to reduce the local thicknesses of walls delimiting the cells 32, 34. Thus, this local thickness can be reduced in a range of between 2.5 and 4 mm, advantageously between 3 mm and 3.5 mm. mm.

In addition, and in general, the demolding of the one-piece shield 8 is facilitated since the large bodies allow a demolding movement of two opposing half-molds in opposite directions along an axis corresponding to the longitudinal axis of the vehicle. Thus, it is not necessary to provide drawers or moving parts in the mold.

In addition, the consistency of the thicknesses in the uprights 28 checkerboard provides a uniform stiffness during a longitudinal depression, for example during a shock at medium speed. Thus, it is possible to obtain a substantially constant load bearing as a function of the displacement, which increases the energy dissipated and reduces the absorption stroke, while remaining under the rating force of the beams 12, 16 defined above.

As a result, the energy of a shock can be dissipated with a reduced stroke, and the solution is very compact. This solution is therefore particularly suitable for low displacement vehicles having a longitudinal shock absorption of less than 250 mm, and in particular less than 200 mm. The uprights 28 have a longitudinal thickness of between 120 and 220 mm. This allows efficient energy absorption, while limiting the cantilever of the shield 8 taken between the plates 20 and the front end of the shield 8.

Furthermore, in pedestrian impact offset laterally, for distances located in particular more than 300 mm from the center of the ribs 30, the reduction of the deceleration is preferably by pure compression, very localized, the uprights 28 checkerboard on a race d about 50 mm.

The upper beam 24 also makes it possible to optimally integrate the shield 8 with the ancillary equipment surrounding it by carrying means for fixing these devices, while maintaining a particularly simple and economical method of production.

Claims (11)

Front assembly for a motor vehicle, of the type comprising at least one pair of upper longitudinal members (12) and at least one pair of lower beam (16) before a chassis (4) of a motor vehicle (2) and plates ( 20), the plates (20) being connected to each other by a metal crosspiece (21) extending opposite the upper longitudinal members (12), characterized in that that it comprises a shield (8) front bumper comprising a frame (22) integral plastic formed of an upper beam (24) and a lower bumper beam (26) and two uprights ( 28) connecting the upper (24) and lower (26) bumper beams, the frame uprights (28) being configured to act as shock absorbers and directly abutting the plates (20), the upper beam (24) extending above the metal crossbar (21) and the plates (20). Front assembly according to claim 1, characterized in that the upper beam (24) comprises fastening means (42) of at least one auxiliary equipment of the motor vehicle. Front assembly according to claim 2, characterized in that the upper beam (24) comprises at least two branches (40) extending substantially perpendicular to the frame (22) towards the rear thereof, said branches (40) comprising fastening means (42) for an auxiliary equipment of the motor vehicle. Front assembly according to any one of claims 1 to 3, characterized in that the upper beam (24) has ribs (46, 48, 50) extending at least on the front face of said beam (24). Front assembly according to claim 4 when dependent on claim 3, characterized in that the upper beam (24) further has ribs on its upper face, said ribs further extending on the legs (40). Front assembly according to any one of claims 1 to 5, characterized in that the lower beam (26) comprises means for fixing at least one auxiliary equipment of the motor vehicle. Front assembly according to any one of claims 1 to 6, characterized in that it comprises an energy absorbing element (27), said element (27) being arranged against the metal crossbar (21) and extending substantially across the frame (22). Front assembly according to any one of claims 1 to 7, characterized in that the uprights (28) have a cellular structure formed of cavities extending longitudinally through the uprights (28) and opening on the rear face and / or front of the shield (8). Front assembly according to claim 8, characterized in that each upright (28) comprises first blind cells (32), closed on the side of the rear face (36) and open on the side of the front face (38), and second blind cells (34) open on the side of the rear face (36) and closed on the side of the front face (28). Front assembly according to any one of claims 1 to 9, characterized in that it further comprises auxiliary equipment (19) extending opposite the rear face of the shield (8), said equipment being fixed at least to the upper beam (24) of said shield (8) by the fixing means (42) of said additional beam (24). Front assembly according to claim 10, characterized in that the auxiliary equipment (19) is fixed to the upper beam (24) by at least one connecting element fixed to the fixing means of the upper beam (24), said element of link being arranged to absorb vibrations between the auxiliary equipment (19) and the shield (8).

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